I have added a 16 ft x 16 ft room to my house and built the addition on posts and concrete piers. The rest of the house is conventional concrete block foundation. I want to enclose the area under the new room and had planned to use concrete-based backer board and cover with stucco. But, I’m concerned that the backerboard will wick water. There is about 24 inches of space between the ground and under the first floor. I will insulate under the floor and put plastic on the ground; but, what can you suggest for enclosing the area under the room?
Chris